The invention relates to a polarisation microscope.
Polarisation microscopy is a technique which uses polarised light to illuminate a sample in order to probe polarisation anisotropy in the sample, which is then used as the contrast mechanism for imaging.
Light may be polarised linearly, i.e. in a single direction, or so that the polarisation state rotates to form circularly or elliptically polarised light. For rotating polarisation, the rotation may be clockwise or anti-clockwise so that the rotation has chirality or handedness. Polarisation microscopy will most commonly look at differences in how rotating polarisation components of opposite handedness propagate through or are reflected from a sample.
The physical properties probed by polarisation anisotropy include: birefringence, luminescence (including fluorescence as used in biological sciences); and diattenuation (sometimes called dichroism, although this latter term can have other meanings).
The development of polarisation microscopy in recent decades owes a great deal to work initiated by Rudolf Oldenbourg at the Marine Biological Laboratory (MBL) in Woods Hole, Mass., USA. The trade name used by this group for microscopes following their design is “PolScope” or “LC-PolScope”, where LC refers to liquid crystal and in particular use of a pair of liquid crystal retarder plates in a so-called universal compensator in which each retarder functions as a linear retarder having a retardance amount which can be adjusted by varying an applied voltage.
The original US patent from the Oldenbourg group is U.S. Pat. No. 5,521,705 [ref. 1] which was filed in 1994 and published in 1996. A later patent is U.S. Pat. No. 7,202,950 [ref. 2] filed in 2003 and published in 2007 describes a development of the original technique which applies a defined set of four or five polarisation states to determine retardance more accurately. A relatively up-to-date description of the polarisation microscope developed from this work is the November 2003 review article: “Polarization microscopy with the LC-PolScope” [ref. 3] which is available online as a pdf document. An abridged version was published in: R. D. Goldman and D. L. Spector, editors. Live Cell Imaging: A Laboratory Manual. Cold Spring Harbor, N.Y.: Cold Spring Harbor Laboratory Press. p 205-37.
The “PolScope” microscope was sold under the trade mark “SpindleView” and is now sold under the trade mark “Oosight”. Originally the microscope was sold by Cambridge Research & Instrumentation (CRi), which was later acquired by Caliper Life Sciences in 2010, which in turn was acquired by Perkin Elmer in 2011. Recently, in 2015, Perkin Elmer sold the PolScope microscope business to Hamilton Thorne. Information and user support is also done in parallel through the “OpenPolScope” organisation also set up by MBL.
A scanning confocal microscope which incorporates polarisation contrast is also known from U.S. Pat. No. 6,856,391 [ref. 4], with a 2000 priority date, which originates from the Biological Research Centre in Szeged, Hungary and is licensed to Zeiss.